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1.
A day with blue skies with few or no clouds, warm, without strong winds, considered by many to be pleasant weather.

or

A 60th anniversary
It's a diamond day outside and I'm not spending one more minute in front of this computer!

It was love at first sight on New Year's Eve 1952, it's a diamond day for Mr & Mrs Couple at the end of 2012.
by fecund January 14, 2013